JPH06137131A - Exhaust emission control device for diesel engine - Google Patents

Abstract

PURPOSE:To supply secondary air of stable flow to a filter without being influenced from exhaust flow and pulsation of a diesel engine, so as to enable stable filter regeneration. CONSTITUTION:This exhaust emission control device for a diesel engine is provided with filters 2, 3 provided on the exhaust passage, and a motor-driven air pump 12 to supply secondary air at regenerating the filters, regenerative combustion gas discharged from the filter during regeneration is taken in a regenerative combustion gas discharge pipe 20, and let flow into an exhaust passage on the lower stream side of a muffler provided on the lower stream side of the filters through the discharge pipe. Exhaust pulsation is small on the lower stream side of the muffler, hence pressure variation in the exhaust discharge pipe 20 is small, and consequently the secondary air flow is stabilized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas purification device having an exhaust passage provided with a particulate filter for collecting diesel particulates discharged from a diesel engine.

[0002]

2. Description of the Related Art Since the exhaust gas of a diesel engine contains a large amount of exhaust particulates, that is, particulates,
The exhaust system of the engine is equipped with a particulate filter (hereinafter referred to as a filter) for collecting the particulates. By the way, if the amount of particulates accumulated inside the filter increases with use, the air permeability will gradually be impaired and engine performance will also deteriorate, so it is necessary to burn the particulates regularly. I won't.

Regarding the filter reproduction processing,
An electric heater is provided on the end face of the filter on the exhaust downstream side to heat the filter when it is regenerated, and the exhaust gas bypasses the filter to supply secondary air from the downstream side to the upstream side of the filter by an air pump or the like to trap it in the filter. An exhaust gas purification device that burns the collected particulates is already known (Japanese Patent Laid-Open No. 223215/1986).
(See Japanese Patent Publication).

[0004]

The exhaust gas purification device described above is relatively stable because it uses the secondary air supplied by an electric air pump or the like, as compared with the case where a part of the exhaust gas is used as the filter regeneration gas. The filter regeneration processing can be performed. However, since this device simply guides the regenerated combustion gas at the time of filter regeneration to the exhaust flow bypassing the filter, fluctuations in the flow rate of exhaust gas due to vehicle operation also affect the secondary air flowing in the filter. However, it was difficult to increase the flow rate fluctuation amount and perform stable filter regeneration every time.

In view of the above-mentioned problems of the conventional device, it is an object of the present invention to provide an exhaust gas purification device which is not easily affected by the fluctuation of the vehicle operating condition and which enables stable filter regeneration at all times.

[0006]

In order to solve the above problems, according to the first invention, a filter for collecting particulates is provided in the exhaust passage of the diesel engine, and the exhaust gas of the filter is exhausted by the air supply means when the filter is regenerated. An exhaust gas purification device for a diesel engine, wherein secondary air is supplied from the downstream side to the upstream side of the filter to burn particulates, and the regenerated combustion gas from the filter is caused to flow to the exhaust passage, the exhaust gas downstream side of the filter. An exhaust gas purification device for a diesel engine is provided in which a muffler is provided in the exhaust gas and the regenerated combustion gas from the filter is introduced into an exhaust passage on the exhaust downstream side of the muffler.

Further, according to the present invention, in the exhaust emission control system for a diesel engine according to the first aspect of the present invention, the regenerated combustion gas is introduced from the upper side of the passage which is substantially perpendicular to the longitudinal direction of the exhaust passage. Is also provided. According to the second aspect of the invention for solving the same problem, a filter for collecting particulates is provided in the exhaust passage of the diesel engine, and the secondary air is supplied to the upstream side from the exhaust downstream side of the filter during filter regeneration. In the exhaust purification device of the diesel engine in which the particulates are burned and the regenerated combustion gas from the filter is caused to flow into the exhaust passage, the regenerated combustion gas from the filter is guided to the exhaust passage through the expansion chamber. An exhaust emission control device for a diesel engine is provided which is characterized by the above.

Further, according to the third aspect of the invention, a filter for collecting particulates is provided in the exhaust passage of the diesel engine, secondary air is supplied at the time of filter regeneration to burn the particulates, and the regeneration combustion from the filter is performed. In a diesel engine exhaust gas purification device in which gas is allowed to flow in an exhaust passage, during engine high-speed operation or vehicle high-speed operation, the regenerated combustion gas from the filter is directly discharged to the atmosphere. An exhaust emission control device is provided.

In the exhaust gas purification apparatus for a diesel engine according to the third aspect of the invention, the filter is composed of two filters juxtaposed with each other in the exhaust passage, and the regeneration processing is performed when one filter is regenerating and the other filter is regenerating. Exhaust gas is introduced into the exhaust passage, and the regenerated combustion gas is introduced into the exhaust passage on the exhaust upstream side of the filter. There is also provided an exhaust emission control device for a diesel engine, which is characterized by being expanded in area.

Further, in the exhaust gas purification apparatus for a diesel engine according to the third aspect of the present invention, when the engine is stopped or the vehicle is stopped, the regenerated combustion gas from the filter is guided to the exhaust passage on the exhaust upstream side of the filter. An exhaust emission control device for a diesel engine is provided.

[0011]

According to the first aspect of the present invention, the exhaust pulsation is attenuated by the muffler, so that if the regenerated combustion gas is guided to the downstream side of the exhaust pulsation, fluctuations in the flow rate of the secondary air can be reduced. According to the invention of claim 2,
Water that tends to be generated on the downstream side of the muffler can be prevented from flowing into the regenerated combustion gas introduction part.

Further, in the invention described in claim 3, the exhaust pulsation is damped by the expansion chamber instead of the muffler.
Further, according to the invention described in claim 4, during high-speed engine operation with large exhaust pulsation or during high-speed operation of the vehicle, the regenerated combustion gas is not returned to the exhaust passage, but is opened to the atmosphere to stabilize the secondary air supply. Plan.

Further, according to the invention as set forth in claim 5, since the exhaust passage cross-sectional area immediately before the exhaust passage introduction portion of the regenerated combustion gas is larger than the other passage cross-sectional areas,
Even when the flow rate of exhaust gas is large, the exhaust gas does not flow into the introduction part. Further, according to the invention as set forth in claim 6, since the regenerated combustion gas is returned to the exhaust passage on the upstream side of the filter when the engine is stopped or the vehicle is stopped, the high temperature combustion gas is purified when passing through the filter. To be done.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below with reference to the drawings by taking as an example an exhaust emission control device having two filters in one exhaust passage. Referring to FIG. 1 showing a schematic configuration of an exhaust emission control device as a first embodiment according to the present invention, reference numeral 1 is an exhaust pipe for guiding exhaust gas from a diesel engine main body E to filters 2 and 3.

The filters 2 and 3 are configured as a honeycomb filter in which plugs are alternately arranged at the ends of a large number of cells in order to collect particulates in the exhaust gas. When collecting particulates, the exhaust gas is exhausted. It enters from the cells 2a and 3a whose upstream ends are open, passes through the partition wall, and then exits outside the filter from the cells 2b and 3b whose downstream ends are open.

A first exhaust control valve 4 and a second exhaust control valve 5 are provided at a branch portion a from the exhaust pipe 1 to each of the filters 2 and 3 and a joining portion b from the filters 2 and 3, For example, when the filter 2 is regenerated, the corresponding valve position shown by the solid line in the figure is occupied, and when the filter 3 is regenerated, the valve position shown by the dotted line is occupied.
The actuators 6 and 7 are driven by
Negative pressure switching valve (VS for controlling vacuum introduction to them)
V) Control circuit (EC for outputting open / close signals to 8 and 9)
U) 10 controls the operation. In addition, each control valve 4, 5
Occupies an intermediate position between the solid line valve position and the dotted line valve position described above, whereby the particulate collection mode by the two filters 2 and 3 is set.

When the corresponding filters are regenerated to the respective branch pipes 1a and 1b on the exhaust upstream side of the merging portion b of the exhaust passage, the secondary air for regeneration is supplied to the filters 2 and 3 to be regenerated.
A secondary air supply pipe 11 is connected, and an electric air pump 12 is provided at the end thereof. Further, in the secondary air supply pipe 11, similar to the second exhaust control valve 7, a supply pipe opening / closing valve 13 that opens and closes the secondary air supply passage from the electric air pump 12 by the VSV 9, and each on the downstream side of the air flow is provided. A first opening / closing valve 14 and a second opening / closing valve 15 for controlling the secondary air supply to the filters 2 and 3 are provided, respectively.

This exhaust gas purification device is constructed as a system for alternately regenerating the filter when regenerating the filter, and an electric heater that alternately energizes and generates heat at the exhaust downstream side ends of the filters 2 and 3 for regenerating the filter. 16, 17 are provided, and the energization ON / OFF of the ECU 10 is controlled. Further, in this exhaust emission control device, in order to detect the filter regeneration timing, that is, the amount of particulates trapped in the filters 2 and 3, the pressure loss value (differential pressure difference) of the entire device is determined by the exhaust pressure before and after the filters 2 and 3. Pressure sensor 1 for detecting
8 is provided, and its output signal is input to the ECU 10.

In addition to the differential pressure sensor 18 described above, the apparatus is provided with an exhaust temperature sensor 19 for detecting the temperature Te of the exhaust gas flowing through the filters 2 and 3, and the ECU 10 as a parameter indicating the engine operating state. The engine speed N, the engine water temperature Thw, the intake air amount Ga, etc. are input, and the vehicle speed value is input from a vehicle speed sensor (not shown).

The ECU 10 then determines the pressure loss under standard operating conditions based on the differential pressure ΔP of the filters 2 and 3 obtained from the differential pressure sensor 18 and the operating information (exhaust temperature Te, intake air amount Ga, etc.) from each sensor. The value is converted into a value ΔP ′, and when it exceeds a predetermined differential pressure value Pa, the filter regeneration time is determined. In the exhaust gas purification apparatus configured as described above, according to this embodiment, the branch pipes 1a and 1b on the exhaust downstream side of the branch portion a of the exhaust passage are provided with the filter 2 to be regenerated at the time of filter regeneration. A regeneration combustion gas discharge pipe 20 for taking in the particulate combustion gas (hereinafter, referred to as regeneration combustion gas) discharged from 3 is connected,
The end is connected to the exhaust pipe 1 on the exhaust downstream side of the muffler 21 provided on the downstream side of the exhaust merging portion b.

Further, like the above-mentioned secondary air supply pipe 11, the regeneration combustion gas discharge pipe 20 has a discharge pipe opening / closing valve 22 for opening and closing the regeneration combustion gas discharge passage, and each filter 2 on the gas flow upstream side thereof. A third on-off valve 23 and a fourth on-off valve 24, which control the gas inflow from the valves 3 and 4, are provided respectively.
Opening and closing is controlled by 8.

The operation at the time of filter regeneration of the exhaust gas purification apparatus as the first embodiment configured as described above will be described below. As described above, the differential pressure sensor 18 detects the
When the converted filter differential pressure ΔP ′ exceeds the predetermined value Pa and the filter regeneration time comes, the ECU 10 causes the VSV to start regeneration from the filter 2 as a device.
A valve opening signal is output to 8 and 9, and the first exhaust control valve 6 and the second exhaust control valve 6
The exhaust control valve 7 is made to occupy the position shown in the figure, and the exhaust gas from the engine body E is guided to the filter 3 as shown by the solid arrow.

On the other hand, in the filter 2, the electric heater 16 is energized to heat the filter to ignite the particulates collected therein, and at the same time, the electric air pump 12 is operated to operate the particulates for particulate combustion.
Next air is supplied only to the filter 2. Therefore, at this time,
In the secondary air supply pipe 11, only the second opening / closing valve 15 is closed to prevent the outflow of secondary air into the branch pipe 1b and the inflow of exhaust gas into the pipe.

The secondary air introduced into the filter 2 is
As shown by the dotted arrow, it flows in the branch pipe 1a in the direction opposite to the exhaust gas, and after burning the particulates, it flows into the regenerated combustion gas exhaust pipe 20 as the regenerated combustion gas through the third on-off valve 23, Eventually, it will be discharged to the exhaust passage on the exhaust downstream side of the muffler 21. Therefore, at this time, in the regeneration combustion gas exhaust pipe 20, the exhaust pipe on-off valve 2
The second and third opening / closing valves 23 are opened, and the fourth opening / closing valve 24 is closed.

When the regeneration of the filter 2 is completed as described above, the apparatus next energizes the electric heater 17 and shifts the regeneration of the filter 3 to the first exhaust control valve 6 and the second exhaust control. The valve position of the valve 7 is moved to the dotted line position, the first opening / closing valve 14 and the third opening / closing valve 23 are closed, and the secondary air is supplied to the filter 3. According to the present embodiment, however, the regeneration combustion gas after particulate combustion is returned to the exhaust passage on the exhaust downstream side of the muffler 21 as described above through this series of filter regeneration processes. Since the magnitude of the exhaust pulsation is extremely small compared to the upstream exhaust passage and the exhaust passage on the upstream side of the muffler, the regenerated combustion gas (and 2) affected by the pressure fluctuation at the regenerated combustion gas outlet portion to the exhaust passage. Next air)
Pulsations within the flow path will be very small and therefore variations in secondary air flow will also be reduced.

As a result, during the filter regeneration, the electric air pump 12 supplies the secondary air having a substantially constant flow rate per hour to the regeneration target filters 2 and 3, so that the filter regeneration failure due to the insufficient oxygen supply (particulate unburned residue). It is possible to avoid the occurrence of problems such as ()) and filter melting loss (increased combustion heat) due to excess. In connection with the first embodiment described above, when the regenerated combustion gas flows into the exhaust passage, the regenerated combustion gas is discharged inside the exhaust pipe 1 downstream of the muffler 21, for example, as partially shown in FIG. The exhaust pipe 20 is bent toward the exhaust downstream side so that it is less susceptible to the influence of exhaust pulsation, or, as shown in FIG. 2 (b), the exhaust pipe 20 is positioned above the exhaust pipe substantially at right angles to the longitudinal direction. The exhaust gas may be further connected to prevent the moisture from flowing into the exhaust pipe downstream of the muffler 21 to prevent the regenerated combustion gas exhaust pipe 20 from being corroded and deteriorated.

FIG. 3 shows a second embodiment of the present invention. In addition, in common with each embodiment of the present invention described below, the same components as those of the previous device will be denoted by the same reference numerals, and the description thereof will be omitted. According to this embodiment, unlike the previous embodiment, the regenerated combustion gas exhaust pipe 20 from each of the filters 2 and 3 is connected to the exhaust passage on the exhaust upstream side of the exhaust branch portion a, but in the middle thereof. Is provided with a large capacity expansion chamber 25.

As described above, the function thereof is that the exhaust pulsation is large in the exhaust passage on the upstream side of the filter. Therefore, when the regenerative combustion gas exhaust pipe 20 is connected to this portion as in this embodiment, the inside of the exhaust pipe is increased. However, since the pulsation is weakened inside the expansion chamber 25 that rapidly increases the passage cross-sectional area, as a result, the secondary air flow rate fluctuation is caused as in the previous embodiment. It will be reduced.

By the way, it is known that the above-mentioned exhaust pulsation is particularly large during high-speed operation of the engine or during high-speed operation of the vehicle. The embodiment shown in FIG. 4 completely eliminates the influence on the secondary air flow rate fluctuation due to the exhaust pulsation under such operating conditions. Therefore, according to the present embodiment, as shown in the figure, the regenerated combustion gas discharge pipe 20 is branched into two in the middle, and one is connected to the exhaust passage downstream of the muffler 21 as in the embodiment shown in FIG. The other is open to the atmosphere. Then, at the time of high-speed operation of the engine or high-speed operation of the vehicle described above, this branch portion releases the regenerated combustion gas flowing from the filters 2 and 3 to the atmosphere, and under other operating conditions as in the first embodiment described above. Regeneration gas control valve 2 that flows into the exhaust passage on the exhaust downstream side of the muffler 21
6 is provided. The regeneration gas control valve 26, like other control valves and on-off valves, is operation-controlled by a VSV 27 that is on / off controlled by the ECU 10 that inputs the current operating conditions.

FIG. 5 is a flow chart for explaining the operation of the ECU 10 which performs the filter regeneration processing of the above-mentioned exhaust gas purification device. This program is stored in a predetermined area in the ECU 10 in advance and is continuously operated during engine operation. Is to be executed. The operation will be described in order. First, in step S51, it is determined whether or not it is the current filter regeneration time based on the filter differential pressure value ΔP from the differential pressure sensor 18 and the operating conditions (N, Te, Ga, etc.) from various sensors.
Only when it is determined Yes (for example, the converted differential pressure ΔP ′> predetermined value Pa), the process proceeds to step S52. As long as the answer is No in step S51, the above-described detection / calculation / determination is repeated.

In step S52, the regeneration of the filter 2 is started first, and specifically, the first exhaust control valve 4 and the second exhaust control valve 5 are moved from the neutral position until then to the position shown in FIG. On-off valves 13, 14, 2
2, 23 are opened, and the electric heater 16 and the electric air pump 12 are operated at about the same time to heat the filter 2 to ignite the particulates.

In the following step S53, it is determined whether or not a predetermined heater energizing time (for example, 5 minutes) has elapsed by looking at the energizing time of the electric heater 16 started as described above. If it is determined, the routine proceeds to step S54, where the engine speed N and the vehicle speed V are read, and predetermined predetermined values (for example,
N: 1000rpm; V: 30km / h)
It is determined whether or not the engine is running at high speed (or the vehicle is running at high speed).

If it is determined Yes in this step S54, if the regenerated combustion gas is allowed to flow into the exhaust passage as it is, it will be affected by a large exhaust pulsation.
In step S55, the VSV 27 is operated to close the regeneration gas control valve 26, and the regeneration combustion gas from the filter 2 is released into the atmosphere. On the other hand, if it is determined No in step S54 and the current driving conditions are not driving the engine and the vehicle at high speed, the routine proceeds to step S56 and VSV2
The regeneration gas control valve 26 is opened by turning off the output to 7, and the regeneration combustion gas is guided to the exhaust passage downstream of the muffler 21. This is because the effect on the secondary air flow rate is small under operating conditions with small exhaust pulsation, so rather, by intentionally returning the regenerated combustion gas to the exhaust passage, it is possible to remove white smoke and odor as much as possible. It is a thing.

The control of the discharge destination of the regenerated combustion gas as described above is executed through a series of filter regeneration processing in the exhaust purification system. Therefore, the routine after each processing in step S55 or 56 returns to the determination processing in step S53, and if it is determined in step S53 that the heater energization time has elapsed (Yes), the particulates in the filter 2 are ignited. If so, the process proceeds to step S57, where the energization of the electric heater 16 ends for the first time.

In step S58 following step S57, it is determined whether or not a predetermined time (for example, 15 minutes) has elapsed, that is, the particulates of the filter 2 are completely burned, by observing the elapsed time from the start of operation of the electric air pump 12. It is determined whether or not Then, in step S58, No
If it is determined that the particulate flame is currently being propagated, the routine proceeds to step S59 and subsequent steps, and the same processing as the series of regenerated combustion gas emission control from step S54 to step S56 described above is performed in step S58 Yes. Execute until it is determined.

If it is judged Yes in step S58 and the particulate combustion of the filter 2 is completed, the routine next proceeds to step S62 to start the regeneration processing of the remaining filters 3. That is, here, the first exhaust control valve 4 and the second exhaust control valve 5 are switched to the positions indicated by the dotted lines in FIG. 4, and this time the on-off valves 14 and 23 are closed to open the on-off valves 15 and 2.
4 is opened, and the processing for starting the energization of the electric heater 17 is executed (the electric air pump 12 continues to operate).

In the filter 3 as well, a series of regeneration processes from step S53 to step S61 described above and regeneration combustion gas emission control according to operating conditions are performed (the description thereof is exactly the same, and is omitted here). ), When the air pump operating time reaches a predetermined time, the routine stops the operation of the electric air pump 12 in step S72 and returns the first and second exhaust control valves 4 and 5 to the neutral position,
Further, the on-off valves 14, 15, 23, 24 are closed to return to the particulate trapping mode, and this routine is ended.

In the third embodiment of the present invention described above, the regenerated combustion gas is released to the atmosphere in the operating state in which the exhaust pulsation is large, and in other operating states, it is returned to the exhaust passage downstream of the muffler so that the exhaust pulsation causes as much as possible. This is intended to reduce the fluctuation of the secondary air flow rate. On the other hand, the fourth shown in FIG.
In the embodiment, the regenerated combustion gas exhaust pipe 20 connected to the exhaust passage downstream of the muffler in the previous embodiment is connected to the exhaust branch portion a.
By connecting to the exhaust pipe 1 on the upstream side of the exhaust gas, and passing the regenerated combustion gas through the filter again, the effect of removing white smoke and odor in the gas by the device is further enhanced.

According to the present embodiment, however, as shown in the figure, the exhaust pipe 1 is provided immediately before the connection portion with the regenerative combustion gas exhaust pipe 20 in order to reduce the pulsation in the exhaust pipe 1, and on the exhaust upstream side thereof. The cross-sectional area of the passage is increased sharply,
A portion corresponding to the expansion chamber of the second embodiment (FIG. 3) is formed. As a result, the exhaust pulsation from the engine is attenuated in this expanded portion as in the second embodiment, the pressure fluctuation inside the regenerated combustion gas exhaust pipe 20 is also reduced, and the secondary air flow rate fluctuation is also reduced.

As shown in an enlarged view inside the circle in FIG. 6, according to the present embodiment, the regenerated combustion gas introducing portion is positioned immediately after the exhaust pipe expansion portion, and therefore, the circled arrow indicates this portion. The negative pressure is generated by the exhaust gas flow indicated by, and the pressure difference also promotes the inflow of the regenerated combustion gas into the exhaust pipe 1, so that the exhaust gas does not flow into the regenerated combustion gas exhaust pipe 20. Absent.

The operation of the exhaust gas purification apparatus during filter regeneration is exactly the same as that of the third embodiment described above, and the emission control of the regeneration combustion gas according to the engine and vehicle operating conditions is performed through the filter regeneration processing. However, in this embodiment, as described above, since the regenerated combustion gas is guided to the exhaust passages on the upstream side of the filters 2 and 3 except when the engine and the vehicle are operating at high speed, as compared with the previous embodiment. The white smoke and odor in the combustion gas can be further removed by passing through the filter, which is to protect the surrounding environment especially when the vehicle is stopped (including engine stoppage) and filter regeneration is continued. It has a remarkable effect.

Although the fourth embodiment of the present invention has been described in which the discharge path of the regenerated combustion gas is changed according to the operating condition, another embodiment is, for example, from the viewpoint of simply reducing exhaust pulsation. As shown in FIG. 7 (a), the regenerated combustion gas may always be caused to flow into the expanded exhaust pipe portion regardless of the operating state, or as shown in FIG. The atmosphere open portion of the regenerated combustion gas discharge pipe 20 in the fourth embodiment may be directly connected to the exhaust pipe portion downstream of the muffler, and the regenerated combustion gas may be introduced into the expanded exhaust pipe portion only when the vehicle is stopped.

In addition, in addition, each embodiment in which the regeneration combustion gas discharge path is not changed according to the operation state [FIG. 1,
2 (a), (b), FIG. 3 and FIG. 7 (a)], only steps S54 to 56 and S59 to 61 are removed from the processing of FIG. 5 described above. The other processing contents are exactly the same as in FIG.

[0044]

As described above, according to the present invention as set forth in claim 1, since the exhaust pulsation is attenuated by the muffler, it is possible to reduce the fluctuation in the flow rate of the secondary air, so that the filter is always stable. Reproduction processing becomes possible. According to the invention described in claim 2, in addition to the above-mentioned effects, inflow of water generated on the downstream side of the muffler to the regeneration combustion gas introduction part is prevented, and deterioration is less likely to occur, and durability of the device is improved. be able to.

Further, in the invention described in claim 3, since the exhaust pulsation is damped by the expansion chamber instead of the muffler,
Similarly, the filter regeneration can be stabilized. According to the invention described in claim 4, since the regenerated combustion gas is discharged to the atmosphere as it is during high-speed engine operation or vehicle high-speed operation in which exhaust pulsation is large, the secondary air flow rate at this time does not fluctuate, and the filter Regeneration stabilizes.

Further, according to the invention described in claim 5, the regenerated combustion gas has a larger exhaust passage cross-sectional area than the other passage cross-sectional areas other than the high speed operation of the engine or the high speed operation of the vehicle. Since it is introduced into the exhaust passage, the pulsation reducing action of that portion stabilizes the secondary air flow rate, and the combustion gas is purified by the filter.
According to the invention of claim 6, in addition to stabilizing the filter regeneration, the regeneration combustion gas is returned to the exhaust passage on the upstream side of the filter when the engine is stopped or the vehicle is stopped. It is purified and does not deteriorate the surrounding environment while the vehicle is stopped.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an exhaust emission control device as a first embodiment of the present invention.

FIG. 2 is a diagram showing two modified examples of the first embodiment, in which the exhaust passage introduction mode of regenerated combustion gas is changed.

FIG. 3 is a schematic configuration diagram of an exhaust emission control device as a second embodiment of the present invention.

FIG. 4 is a schematic configuration diagram of an exhaust emission control device as a third embodiment of the present invention.

5 is a flow chart for explaining the operation of the device shown in FIG. 4 during filter regeneration.

FIG. 6 is a schematic configuration diagram of an exhaust emission control device as a fourth embodiment of the present invention.

FIG. 7 is a diagram similar to the fourth embodiment and showing two modified embodiments in which the introduction mode of regenerated combustion gas is changed.

[Explanation of symbols]

 1 ... Exhaust pipe 2, 3 ... Filter 10 ... Control circuit 12 ... Electric air pump 20 ... Regenerated combustion gas exhaust pipe 21 ... Muffler E ... Engine body

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kotaro Hayashi 1 Toyota Town, Toyota City, Aichi Prefecture, Toyota Motor Corporation (72) Inventor Mori Oki 1-1, Showa Town, Kariya City, Aichi Prefecture NIPPON DENSO CORPORATION In the company

Claims (6)

[Claims] 1. A filter for collecting particulates is provided in an exhaust passage of a diesel engine, and when the filter is regenerated, secondary air for regeneration is supplied to the filter from the exhaust downstream side to burn the particulates, and the filter is further filtered. In the exhaust purification device of the diesel engine, which allows the regenerated combustion gas from the engine to flow to the exhaust passage, a muffler is provided on the exhaust downstream side of the filter,
An exhaust emission control device for a diesel engine, wherein the regenerated combustion gas from the filter is introduced into an exhaust passage on an exhaust downstream side of the muffler. 2. The exhaust emission control device for a diesel engine according to claim 1, wherein the regenerated combustion gas is introduced from a passage upper side that is substantially perpendicular to the exhaust passage longitudinal direction. 3. A filter for collecting particulates is provided in an exhaust passage of a diesel engine, secondary air is supplied at the time of filter regeneration to burn the particulates, and regenerated combustion gas from the filter is flowed to the exhaust passage. In the exhaust emission control device for a diesel engine described above, the regenerated combustion gas from the filter is introduced into the exhaust passage through an expansion chamber. 4. A filter for collecting particulates is provided in an exhaust passage of a diesel engine, secondary air is supplied at the time of filter regeneration to burn the particulates, and regenerated combustion gas from the filter is flowed to the exhaust passage. The exhaust emission control device for a diesel engine, wherein the regenerated combustion gas from the filter is directly discharged to the atmosphere during high-speed engine operation or vehicle high-speed operation. 5. The filter is composed of two filters juxtaposed to the exhaust passage, and in the regeneration process, when one filter is regenerating, exhaust gas is introduced to the other filter, and the regenerated combustion gas is The exhaust passage cross-sectional area of the exhaust gas is guided to the exhaust passage upstream of the filter and close to the exhaust passage introduction portion of the regenerated combustion gas, and the exhaust passage sectional area immediately before the exhaust passage is enlarged as compared with other passage sectional areas. 4. An exhaust emission control device for a diesel engine according to item 4. 6. When the engine is stopped or the vehicle is stopped,
The regenerated combustion gas from the filter is guided to the exhaust passage on the exhaust upstream side of the filter.
Exhaust gas purification device for diesel engine according to.